Elberoth

I thought it may be an interesting (if horryfing !) read for many A5/S5 owners.

In short, with direct injection, fuel is sprayed directly into the combustion chamber. Nothing is truly cleaning the intake valves from PCV gunk & blowby.

After just a few thousands of miles, FSI engine starts to look like this, impeding performance by as much as 10% (so ~40hp on an S5 !)

(pictured RS4 engine with just 40.000 miles)



and here how it should look line (with all the gunk removed):



Seems that all FSI engines have this problem S5 4.2FSI, RS4/R8 4.2FSI, 2.0FSI etc.

You don't really see this issue as much with older port injection engines (non FSI engines) because fuel is cleaning the valve & surrounding area.

More on this topic (RS4 forum):

Link

keman

I figured this was happening. On the 2.0T there is a flapper plate at the base of the intake manifold that tilts and increases the velocity of air entering the cylinders when there's no boost at low RPM for a bit more torque. It gets munged up with this and throws a code.

Eventually burning out the actuator- three digits here in the cost range, questionable warranty coverage in the VW arena as usual. Seen some people have to pay, seen others get it covered. One that recently showed up on my 2006 GTI with the 2.0T.

I foresee a custom oil seperator for my S5 and GTI in the PCV circuit. Or eliminating it.

It can blowby all it wants, the PCV system doesn't move a lot of air.

I'm not suggesting eliminating it per se-- on the contrary I DO want moisture and fuel vapors etc being pulled from the air inside the engines rotating areas. It just doesn't have to be pulled from the pre-MAF loop, and it doesn't have to be thrown back into the intake to be "burned". It can and will be completely seperated from the engine's intake. This is all the proof I needed to start this project with a bang.

Keep in mind that while those aren't the exhaust valves, they get mighty hot and that's why everything looks cooked and crusty. When it was first pulled from the crankcase, it was originally just "oil", "fuel" and "air".

I wonder what AoA will do for this problem besides blame it on our crappy fuel.

keman

Oh and in case peeps wonder why I call my GTI a 2006 is because it has half of 2006's parts and half of 2007's. It IS an 07, but it has the 2006's headlight washers, etc. It's such a freakshow that it took VW 32 days and two blown up (physically exploded, metal chunks going everywhere) A/C compressors to come up with a COMPLETE TOTAL custom solution-- every A/C line, hose, fitting, evap, condenser, bracket, everything... when the A/C died at 10k miles. 28 billable hours of labor, thousands in parts, a thousand just for my rental, and you bet I made them pay my monthly payment. I was going to lemon it but got lazy... and kinda grew attached to it. A/C still blows cold. They lost money selling me that car, for sure.

elf_cruiser

If you do the PVC bypass - please take some pics and do a write-up - My motor has just over 3k on it now, and I'd like to take prevenetative measures...

keman

You can count on it. Hehehe. I haven't done a tech writeup in like a decade.

sesame60

Please keep us posted on what you come up with. My car is new (400 miles) and I'm definitely interested in what can be done to help prevent or reduce carbon buildup.

Thanks.

Mike

would this also include the 2009 3.2 VR6 [TT]?
thanks
Mike

CAP930/A5

What can we do to avoid it???????

VictoR6

There's some documentation about this problem in one of VAG's patent applications regarding their DI engines. Part of it describes several methods of preventing carbon buildup. One of the solutions included performing an "Italian tune-up" to burn away the residue (I'm not kidding, there's link of the patent somewhere and I read the whole thing). Specifically, you rev it past 3k rpms for 20 minutes, and that makes the engine hot enough to clear any obstructive build-up in the intakes. It's probably a good idea to do it at least once prior to a scheduled oil change.

nemohm

The only logical action seems to be to employ your warranty (for those having warranty) for the rest - just dump that fine product (might keep the body and replace the engine only),
or ponder over any class action endeavors.